installing strategy/delete problems

[pkc]

I am about to distribute to a bunch of academics a software device that I fear they won't install properly (it has to be in a folder). 

I've modified the application so that the first time it launches, it will in essence re-install itself (by downloading and launching a separate stack that copies the application to its own folder and create its support files).  The application closes itself, initiates an ancillary stack that creates the folder, copies the app to it, creates the support files, launches the properly sited app, and then hides itself (it will close when the app next closes).

This means that the original app, which will be in the default download location, must disappear after the auxiliary stack has created and launched the new copy of the application. Unfortunately, all this works extremely well except the last step.  I can't get the ancillary stack to delete the original application. Every variation (delete, delete file, delete folder, delete URL, using or not using the ".app" suffix for the app file), brings up the result "can't delete that file."  I have checked carefully to make sure all paths are correct.

There's some missing element I'm not understanding.  The file to be deleted is a Revolution-created app. Is OS 10.4.1 nevertheless refusing me permission to delete it (the info screen does not say so)?  Can only documents be deleted, and not executables (aren't they just documents?)? 

I thought of using Applescript to get this done, but I it looks like I have to specify a location in the script for the original, instead of carrying over some kind of defaultfolder from the Revolution script. I don't think it will be suitable.  Is there any way delete an app from Revolution? Or, can I just make it disappear by some other means?